[29.02] Chemistry in the Dusty Coma of Comet Hale-Bopp

Recent progress on a multifluid, hydrodynamic model is
presented for the dusty gas flow in the inner coma of comet
Hale-Bopp at several heliocentric distances. The simulations
are based on a 1-D neutral coma model with detailed photo
and gas-phase chemistry and dust entrainment by the gas, a
separate energy balance for the electrons, separate flow of
the neutral gas, fast neutral atomic and molecular hydrogen,
and dust entrainment with fragmentation. The model accounts
for three sources of gas release: sublimation from surface
ices, transport of gas from subsurface regions through the
surface, and release of gas from dust in the coma. This
permits a consistent study of the importance and strength of
each possible source for a variety of gas-phase species. The
simulations allow a study of the changes with heliocentric
distance of features within a cometary coma, e.g., spatial
distributions of gas-phase species and dust of various sizes
and the velocity and temperature profiles. In particular,
the model is used to probe spatial distributions of
gas-phase species (e.g., CN, CH, C3, C2, HCN, HNC, CO)
and dust, and the velocity and temperature structure to
understand the complex gas-phase chemistry that occurs in
the inner coma. Comparisons with observations are made where
available to characterize the environment surrounding comet
Hale-Bopp and to aid in assimilating a variety of diverse
observations of this unique comet.